Numerous devices are already known for separately storing two components which are to be mixed extemporaneously on first use.
German utility model (Gebranchsmuster) G 8624488.4 discloses a device having one of its compartments constituted by a flask presenting an externally threaded neck at its top end, while its other compartment is formed by a tubular portion engaged inside said neck, closed at its bottom end by a removable plug, and provided at its top end with a dispensing endpiece defining an outlet channel that is closed by a closure cap. The plug is held by friction in said tubular portion and bears axially at its periphery against a shoulder formed at the base of said neck. A closure rod extends the plug upwards and engages in said outlet channel so long as the plug bears against said shoulder. This makes it possible to prevent the component contained in the tubular portion being distributed before it has been mixed with the component present in the flask. The tubular portion is secured to an external skirt in screw engagement on the thread of the neck and making it possible, when rotated in the unscrewing direction, to raise the tubular portion inside the neck. After the tubular portion has travelled over a predetermined upward stroke, the plug which is held axially by the shoulder formed at the base of the neck ceases to be held thereby, and drops into the flask, thus enabling the component contained in the tubular portion to mix with the component contained in the flask. That known device does not provide entire satisfaction, in particular because it is difficult to fill the tubular portion. Specifically, it is not possible to insert a substance via the dispensing endpiece when the plug is engaged in the tubular portion since the closure rod then closes the outlet channel. It is therefore necessary to fill the tubular portion before the plug has been put into place therein, and in that known device the threaded neck of the flask is made removable for that purpose. In addition, the tubular portion is filled with the dispensing endpiece pointing downwards, and closed by the closure cap. When the substance is in powder form, it can fill the outlet channel and subsequently interfere with putting the plug into place by preventing the closure rod being inserted in the outlet channel. When the substance is a liquid, traces of the liquid can remain in the outlet channel and that is disadvantageous when the substance is an irritant since the user can be exposed to the substance on unscrewing the closure cap.